International Journal of Preventive Medicine (Int J Prev Med)2008-78024120130505234238ENFood Security Research Center, Faculty of Nutrition and Food Sciences, Isfahan University of Medical Sciences, Isfahan, IranDepartment of Clinical Nutrition, Faculty of Nutrition and Food Sciences, Isfahan University of Medical Sciences, Isfahan, IranIsfahan Neurosciences Research Center, Isfahan University of Medical Sciences, Isfahan, Iran20130505<p><strong>Background: </strong>Diabetes is one of the most common chronic diseases in which antioxidant capacity changes. Omega‑3 fatty acids have extensive biological effects including their advantage on lipoprotein metabolism, platelet function, cytokine production, clotting, fibrinolysis, and inflammatory factors. This study aimed to investigate the effect of omega‑3 fatty acid supplements on antioxidant capacity in patients with type 2 diabetes.</p> <p><strong>Methods: </strong>This clinical trial enrolled 71 women with type 2 diabetes in two case (treated with omega‑3 capsules) and control (treated with placebo) groups. In the first stage, participants filled out a demographics questionnaire including age, height, weight, waist circumference, and hip circumference.Their blood sample was taken to evaluate glycosylated hemoglobin and antioxidant capacity. Then the case group received intervention for 8 weeks and weight, waist circumference, and hip circumference were measured and a blood sample was taken again. The data were analyzed using SPSS 18 software.</p> <p><strong>Results: </strong>The mean difference of antioxidant capacity before and after intervention was significant (<em>P </em>&lt; 0.001). Antioxidant capacity increased in the case group and reduced in the control group.</p> <p><strong>Conclusions: </strong>With regard to the results of the present study, patients with type 2 diabetes increase their antioxidant capacity, enhance their antioxidant defense system, and probably prevent diabetes complications and related disease progress by taking omega‑3 supplements.</p> <strong>Keywords: </strong>Antioxidant capacity, omega‑3 supplement, type 2 diabeteshttp://ijpm.mui.ac.ir/index.php/ijpm/article/view/1166http://ijpm.mui.ac.ir/index.php/ijpm/article/download/1166/953